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Book/Report | FZJ-2018-00636 |
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1976
Kernforschungsanlage Jülich, Verlag
Jülich
Please use a persistent id in citations: http://hdl.handle.net/2128/16626
Report No.: Juel-1268
Abstract: In the next generation of fusion experiments, which are planned to reach thermonuclear ignition conditions, a deuterium-tritium mixture will be used as fuel. If significant D-T burning is achieved in these devices a large number of 14.1 MeV neutrons will be produced which will activate the components used in the experiments. The resulting activation radiation will create additional problems of access to the machine for maintenance and repair, which should be taken into account in the design and construction phase of these experiments. To give an idea of the dose rates to be expected, some activation calculations for a typical large Tokamak ignition experiment are presented. It is assumed that the machine is operated in a pulsed mode at an average of 100 plasma discharges within one week and that 10$^{20}$ neutrons per pulse are produced. The investigation shows that 30 days after shutdown of the machine the total absorbed dose rate in the vicinity of the device is about 0.2 rem/h which limits the working time in this area to about 10 h per quarter. For repairs inside the vacuum vessel or dismantling of the machine it is assumed that the machine can be divided into eight identical segments. The dose rates from an isolated segment and from the remaining part of the machine after removal of one segment are calculated. The results for both cases are of the same order of magnitude and are in the range of 2 to 4 rem/h for decay times between 5 and 30 days. Hence, all repairs inside the vacuum vessel or dismantling of the machine must be done by remote control.
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